As is known in the art, free-space optical (FSO) laser communications (lasercom) links are used for high-bandwidth data transmission where optical fiber is not practical. These links are costly in terms of dollars, size, weight, and power (SWaP). For FSO network access nodes, as with most access nodes, the average data rate for each user is typically much lower than the link line rate.
Prior art approaches to multiple access for FSO lasercom have used dedicated facilities. The earliest approaches duplicated the complete transmit/receive (Tx/Rx) and beam control apparatus for each user. In essence, a single access system with full data rate for each user was used. While this approach is appropriate for backbone networks, it is not cost-effective for access networks and provides no scaling benefit as the number of users in an access network increases. Thus, the cost and SWaP grow linearly with the number of users.
More advanced prior approaches share the beam forming system between users, but require separate Tx/Rx and fine beam steering/tracking modules for each user. While this provides some scaling benefit, the most expensive modules must still be duplicated for each user. In addition, all users must be within the field-of-view of a single, high-quality telescope. This restricts the angular distribution of users to a cone with about a two-degree full angle.